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One of my CZ52's has a nasty trigger slap every now and then. It seems like I read somewhere how to fix it but I don't remember where. UncleJaque was that you?
 

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what is trigger slap?
Trigger slap is when the trigger is resetting while it whacks your finger. That terminology may not be correct, but our bersa .380 trigger certainly slaps me every time i shoot it. Your finger will start to go numb. Not the best for trigger control. My CZ used to but it ground out after a few hundred rounds/half dozen cleanings. I'd just clean the gun and make sure everything is in the right place. A pin may have backed out or a spring slipped out of a slot.

I'm remembering someone had a very complicated, well-thought out means of finding and fixing trigger slap on the old boards, but i don't know where it is at the moment. No specific diagnoses, sorry.
 

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Rummaging Through the Archives...

Ahh yes; let me see here...

(Rummage; rummage...)

A "Team" of us regular Contributors and Czechophiles got together and collaboratively diagnosed and developed an effective correction for TSP. As far as I know, it's worked every time it's been tried.

Oh!; here it is! (From Jan. of 2004):


"According to my calculations, there are essentially two places where this "trigger-slap" can be originating.
Now ccg, as clever as you are, you might be able to locate another one I have yet to consider, and you're a daisy if ye do!

The first one I thought of was the "Disconnect" lug that extends from the top of the trigger actuator bar on the right side, under the sideplate that runs from the trigger back to hook under the hammer pivot (the thing that has a little nut on the end that you can see if you take the right grip panel off). The Disconnect lug or "hand" sticks up between the grip panel and the lower edge of the slide, and if you have the slide off and pull the trigger with the safety off, you can see it waggle up and down. The top edge of it is tilted a little.

Look at the bottom of your slide, and you will see the corresponding quarter-circle cutout near it's right edge (which will be on the left if you're holding the slide upside-down). This is to allow the hand to extend up into the cutout when the slide is in battery, allowing the actuator to bear on the sear and drop the hammer. If the slide is out of battery, the hand is blocked by the slide rail (where it's not cut-out) and the actuator is pushed down and out of articulation with the sear - so pulling the trigger will not disengage the sear, drop the hammer, or fire the pistol.

At least that's how it's supposed to work; it seems, however, that if the slide is just a little bit - say about 1/8 of an inch from being completely closed - it is apt to fire anyway.
This means that an out-of-spec cartridge or short headspace on your CZ-52 might cause it to fire a wee bit out-of-battery, which is not all that good a thing, you know.

Now there are two actions of the slide in cycling operation, as I see it, which can translate to an impact or impulse of energy back to the trigger.

If you find any more, ccg (or anyone else out there), please advise us, so that we may include them into the existing paradigm.

Since it is reported that installation of a Firing Pin upgrade has cured this issue at least once so far, I have moved away from the actuator disconnect as the prime suspect and focused instead on the firing pin lock-out plunger.

At rest, the plunger is moved to it's lower position by the spring. In this position, it's "hook" engages the corresponding notch or cut-out on the top rear of the FP, locking it from moving forward or striking the primer. The bottom of the plunger should be flush with the central rail set, consisting of a raised rib running down the center of the breech end of the inside of the slide, which has a narrow notch milled along it's center.

..................................


When the slide is in place, the bottom end which is cut away on one side, leaving a semi-circular bearing surface, should rest upon the end of the lifter arm extension of the sear.



Again with the safety off and slide removed, you can see this little arm directly in front of the hammer move up when the trigger is pulled, and drop back down when it is released.

................


When the arm is lifted, you may notice that it's articulating surface is tilted towards the breech end of the frame.

When the slide is in place, and the trigger is activated, the lifter engages the firing pin lockout plunger in the slide and lifts it. The locking "hook" lifts clear of the firing pin notch, allowing the pin to fly forward and strike the primer of the cartridge when struck by the falling hammer. As the hammer rebounds, the angled face of the "hook" is supposed to cam the firing pin back into it's rearward position, and as the action unlocks and the slide begins to move to the rear, the plunger backs off of the lifter hand and is pushed back down by it's spring, re-locking the firing pin until the trigger is pulled for the next shot.

At least that's how it's supposed to work, as near as I can tell.

Now if for some reason the plunger is coming back down a little too far, or the sear is rotating a little further than it should, that little arm is still going to be sticking up when the slide comes back for more and the bottom of the plunger is apt to fetch it a healthy whack, smacking it right back down smartly - and the stronger your recoil spring, in all likelihood, the harder the whack.

If you trace the path of where that energy impulse is likely to be transmitted, guess what?; it ends up right at the trigger, smacking it forward against your finger about a nanosecond after your shot broke.

Make sense to you?

Now if you look at where the plunger goes in a slide that's been outfitted with a Harrington system, you might notice that the lockout plunger is rather conspicuous by it's absence.
There is, instead, a little hole through the pin shaft itself through which you poke a little pin to disengage a much shorter little retaining lug that is provided with the system in order to remove the FP.

The job of holding the pin back from bumps, jars, and the inertia from when the slide slams home into battery is taken over by a stout little rebounder spring coiled around the Harrington Pin's nose. So the long and the short of it is, that there is nothing at all to strike the sear's lifter-arm as the slide runs home, thus no slap-down, and no corresponding trigger-slap.

This is not to say that some CZ-52s might not be having an issue with their trigger actuator disconnector hand getting fouled up somehow in it's little raceway in the slide; If that little hand gets smacked backwards as the slide comes back in recoil, it is going to snatch the bar backwards right along with it.... and the forward end of said bar is attached by a little pin to the top of the trigger, above the trigger's pivot-pin. Now a backwards snatch on top of the trigger is going to be translated into what kind of a whack underneath said fulcrum point? And how is your trigger-finger apt to perceive that sort of an energy impulse?

I rest my case, and stand ready for cross - examination.

Oh; BTW; I would, while I had the slide off, check that little "hand" as well as the groove along that side of the slide that it runs in for bright wear spots, burrs, nicks, or other signs of unusual bearing or collision.

Now if any of you with a trigger - slapping Czech-O-Matic are able to cure your weapon of this bad habit by application of any of the above speculation, I would appreciate knowing about it - and it just might make my day as well as yours!"

And another post about 2 months later:

"
UJ in ME

<b> In my original theory of the causative factors in “Trigger Slap Phenomenon” I proposed that there may be more than one cause for it, and aside from the problematic articulation between the firing pin lockout lug and the sear lifter arm, the disconnecter tab on the trigger actuator bar was a prime suspect.

It would appear that Johnnymicic has arrived at the same conclusion, which I have never renounced even though some remedial tweakage over on the sear/lug side seems to have cured the TSP on at least 2 CZ-52s that we know of.

These observations seem to bear my original suspicions out, at least to some extent.

There are a couple of ways that a misaligned disconnector tab could cause TSP;
As you so aptly point out, after the trigger “breaks” and the pistol fires, the sear is still in the lifted position, where the “arm” that projects forward from the pivot point is lifted up, pushing the FP lug up and unlocking the firing pin, enabling it to fly forward from the hammer’s impact and fire the round.

Thanks to a groove milled down the center of the keel of the slide, the recoiling slide won’t tear that sear arm off even if it fails to snap back down into battery – which it is supposed to do as soon as the trigger actuator bar is pushed downwards by the action of the recoiling slide running the semicircular cut-out in the right (ejection port side) wall, (which you can see if you flip your slide over – a little forward of the hole where the Firing Pin Lockout Lug goes) back beyond the upward – sticking tab.
..............


If the tab is not aligned with the side wall of the slide, then the bottom edge of the wall forward of the cutout is not going to push it down to disconnect it from the sear so that it can “snap” back down.

When the slide comes back to chamber the next round, the lockout lug, held down by it’s return spring, is going to collide with the lifted arm of the sear, driving it forward and down somewhat violently. That impulse is going to be transmitted back through the actuator bar to the trigger (assuming that the actuator bar has not “disconnected” like it is supposed to) and thus driving the lower blade of the trigger forward into your hapless finger.

...


Now here’s what’s still perplexing me just a little;

If the disconnecter does it’s job and releases the sear as soon as the slide starts back like it’s supposed to, then a smack to the sear should NOT be coming back along the transfer bar to your finger.

But then, if it did not, then unless you are very quick and release the trigger before the slide gets all the way back to cock the hammer, the sear will still be held “Up” by the trigger and unable to engage the notches in the hammer base – meaning the hammer will just follow the slide back down and not stay cocked.

So is your Czech-O-Matic disconnecting, or not disconnecting as the action cycles..???

Without examining the patient myself, it’s hard to tell, really.

But just in case you ain’t sufficiently confused yet….;

If your disconnect tab is misaligned in any way, the recoiling slide, instead of just camming it down, is going to fetch it a whack – or at least drag it quickly (hard to tell the difference when it only takes nanoseconds) to the rear, and the rest of the actuator bar right along with it. That in turn will yank the top of the trigger assembly backward, causing the blade which is UNDER the pivot pin to… it’s pretty simple physics, really – jerk forward.

Instead of “disconnecting” as the proper downward push on the actuator would do, this action would force the trigger forward as it backs the little hook on the bar that engages the sear off of it, allowing it to drop it’s “arm” out of the way of the moving FP lockout lug and re-engage the hammer, holding it back when the slide returns to battery.

So pushing down OR back on the actuator bar accomplishes the same function, only in different ways – except in the “back” mode it can be rough on both the trigger finger and the innards of the pistol.

By the wear patterns described, it seems that your slide is over-riding the disconnector tab on your trigger actuator bar. This could be a function of a worn or defective slide, or a bent or warped actuator bar.

If the latter, it may be possible to repair the bar – but Czech steel tends to be rather hard and apt to break before it will bend – especially if it has already been bent out of whack and we attempt to bend it back.
A good Machinist could probably draw the temper, straighten out the bar, and re-temper it… but you might be ahead of the game to just replace it.

The theory that seemed to help Banker and a couple of other guys was that the sear arm, even in it’s disconnected position, might be sticking up just a little higher than it is supposed to and taking a hit from the disconnect lug/tumbler as the slide returns to battery.
This made sense, as others noticed that their TSP went away as soon as they installed a Harrington firing Pin Kit, which eliminates the lockout tumbler entirely.

They apparently polished the lockout lug and put a little radius on the bottom edge, so that it would ride up and over any projecting tip of the sear arm rather than colliding with it.

For them, it seemed to work.

This pistol, however, may be a different story.

Try, if you will:

With the weapon CLEARED of ammo and magazine, and double-checked;

Cycle the action a few times and feel for any impulses on the trigger finger. Does the hammer stay cocked with the trigger still all the way back, and won’t fall until the trigger is released (you should hear a little but audible “snap” or “click” when the trigger is released)?

If you can feel the impulse, does the slide seem to hang up or meet resistance about the same time?

Again, if you can feel the forward push on the trigger while you cycle the slide manually – try removing your firing pin and lockout tumbler completely.
Put the slide back onto the frame, and jack the slide some more. Is the “impulse” still there?

If it is, then your problem is likely to be found in the trigger actuator bar / disconnecter system.

If not, then the issue may be between the sear lifter arm and the lockout tumbler; try smoothing out that bottom surface (trigger pull will benefit from polishing the whole thing) and putting just a little radius – no more than what you can see around a primer – around the edge of the bottom flat.

Personally, I do not see any advantage in clipping the lockout Tumbler Return spring, and do not recommend the practice – but a lot of other people do.

HTH – Please keep in touch and let us know how it works for you."

UJ in ME
 

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Uncle Jaque that was as detailed a response to any post I've ever read!

AKs are notorious for trigger slap never encountered it on a 52.
 

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Discussion Starter #7
Thanks for the reply Jaque, I knew you'd know how to fix it :) One thing, the pistol that it happens on more does NOT have the "circle Z" on it. My understanding is that this is a stamp put in when the de-cocker was refurbed before import. Oddly, the decocker works on this pistol per the pencil test. I have to wonder if it's related.
 

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Well, anything is possible I suppose - but I rather doubt it, really.

Regardless of how well a decocker performs on the pencil test, the general consensus among experienced CZ-52 users is that they are not to be trusted no matter what.

I took the decock shoulder on my safety drum right out of articulation on one of my Czech-O-Matics so that it simply won't de-cock any more, just to be on the safe side.

Probably the simplest way to correct the TSP would be to install a Harrington firing pin system. Never known it to fail.

As to AKs I would not have a clue. Dont own one.
They never appealed to me very much, actually.
 

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I have not noticed tsp with my 52,but i run mine a little on the wet side mostly for the roller locks if these are to dry they will chew up the lock ass. and barrel. my manuel says to use 40 wt. oil on the locks.
 

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I've got a nice condition CZ52 I've had for a few years. When I bought it I immediately ordered new rollers, new recoil spring and new sear spring.

I've never experienced trigger slap with it. It's very comfortable to shoot for such a fireballer!

I had a post-war Mauser HSc that had horrible trigger slap. You'd fire 1 magazine and it felt like you'd closed your finger in a car door. :(
 

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Probably the simplest way to correct the TSP would be to install a Harrington firing pin system. Never known it to fail.
I did that with mine - installed Harrington firing pin and rollers. Used a little gun grease and oil in the proper places...the action is nice and sweet on mine :)
 

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Trigger work

I saw an article in an issue of Shotgun News (Vol.56, Iss.12, ppg20-22) witch talks about the CZ52 and some common tuneups...sights as well as trigger creep and overtravel are discussed. And I have it from an old WW2 vet that TSP can also be dealt with by removing overtravel.

Also, a word of warning if buying an aftermarket barrel....have the headspacing measured before firing or modifying the ramp. This is so you can return it if it's wrong. Mine was too great and 9 of 10 rnds (new S&B ammo) experience spliting of the case neck...not good if you reload as I do.
 

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I saw an article in an issue of Shotgun News (Vol.56, Iss.12, ppg20-22) witch talks about the CZ52 and some common tuneups...sights as well as trigger creep and overtravel are discussed. And I have it from an old WW2 vet that TSP can also be dealt with by removing overtravel.

Also, a word of warning if buying an aftermarket barrel....have the headspacing measured before firing or modifying the ramp. This is so you can return it if it's wrong. Mine was too great and 9 of 10 rnds (new S&B ammo) experience spliting of the case neck...not good if you reload as I do.
What brand of aftermarket barrel are you using?
 

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Headspace - 7.62 X 25mm

I'm not sure if anyone makes a headspace gauge for the X25 - I suppose they do, but they are probably not real plentiful.

Remember that this round headspaces (or is supposed to) on the shoulder, like a rifle round, and not on the case mouth, as most straight cased semi automatic pistol rounds do.

I took some measurements, including how much head of a chambered round I had sticking out of the breech on one of my Czech-O-Matics; this might give you at least a ballpark idea of how deep the chamber is supposed to be:

...


I measured .092" between the surface of the cartridge head and the breech face at the top of the barrel - FWIW.

If you reload, I suppose you could make up some dummy rounds to simulate "Go / No-Go" gauges. You'd sort of have to know what you're dong though, and testing on a semi auto pistol would not be as definitive as it is on a bolt action rifle where it's pretty obvious if the bolt is going to close on it or not. With a slide, a long round can chamber slightly out of battery and be hard to detect as such. And I have found that the CZ-52 hammer WILL drop in that condition, despite the interrupter device.
 

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I believe Uncle Jaque has nicely summarized all the previous postings (search CZ-52 and trigger slap in the forums for archived posts). There is considerable lengthy discussion of the subject both here and in other forums on the web.
It boils down to two potential sources, the firing pin lug ... easily corrected with a Harrington set which is a vast improvement in the gun anyway, or the tab on the disconnector bar.

The CZ-52 is worthy of the time and effort for a complete overhaul and trigger job as it can be extremely accurate and fun to shoot once properly tuned up. Much of the information on how to do that has already been posted so dig through the archives.

Mine was an absolute and painful jackhammer that beat my finger sore for a month! The source was not the firing pin lug, that was replaced with the Harrington. It came down to modification and some filing on the disconnector tab. The little bugger is a joy to shoot now and 300% improved over what it started out as.

DO READ all the archived posts as there are some very important pointers in taking it apart and putting it back together should you decide to explore the innards!
Tiny springs will vanish into thin air!
 
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